<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>点击</button>
    <script>
        // function fn(){
        //     console.log(this);
        // }
        // window.fn()

        const btn = document.querySelector('button')
        btn.addEventListener('click',function (){
            console.log(this);
            this.style.color = 'red'
            //谁调用，this就是谁
        })
    </script>
</body>
</html>